The present invention relates generally to load position sensing devices for load carriers, such as fork lifts on fork lift trucks, where a load is to be transported by a carrier device that potentially may damage the load if a proper position is not maintained by the carrier.
Several types of position sensing devices exist in the art. Position sensing devices, such as in U.S. Pat. No. 3,034,675, have been designed to relate the position of a shelf below the forks of a lift truck to indicate when the forks have been extended a proper distance inwardly of the shelf edges. Other bumper type position sensors have been utilized to detect the existence of a load, such as in U.S. Pat. No. 3,560,678.
The problems faced with load carriers, such as fork lifts, in transporting frangible goods, however, are unique to a warehouse storage environment and are long-standing in the field. Warehouses store packaged goods such as bottles, cans, food stuffs, and other products on pallets. The packages generally have enough strength to support other packages of the same type in stacking the packages in a vertical direction, but the siding of the packages generally is not designed to withstand lateral loads caused by shifting or undue compression of the packages in order to keep the packaging costs to a minimum.
If the lift is too close to the load, the vertically extending support means will push the packages on the pallet load too closely together when lifted and increase the possibility of product damage. If the pallet load is not close enough to the vertical support means of the lift, the pallet load will tip away from the lift as it is raised, thereby again forcing the packages together or spilling a portion of the load. Also, when the fork lift approaches a pallet load, the verticl support means of the lift may get too close to the load, directly apply a lateral force to the load on the pallet, and damage the goods.
Accordingly, it is one object of the present invention to provide a load position sensing device for fork lifts or other similar load carriers which transport pallet loads of potentially frangible materials, which indicates to the operator of the load carrier that the load is in a proper position to be lifted and transported, whereby the possibility of product damage will be reduced by having the vertical support means of the load carrier a proper distance from the load when the load is lifted.
Another important consideration in the transport of pallet loads, particularly where the carrier device is a fork lift, is side-to-side tipping due to misplacement of the forks under the pallet prior to raising the forks. Accordingly, it is another object of the invention to provide a load position sensing device that also will accomplish the above objects without totally obscuring the operator's vision of the forks of the fork lift, so that the operator may be able to obtain proper lateral placement of the forks.
Another object of the present invention is to provide a device that is sturdy and durable in a fast-paced, rough-handling warehouse storage environment, yet relatively easy to manufacture and repair.
Other objects and advantages of the instant invention will be apparent in the following specification, claims and drawings.